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采用两步法制备稳定性较好的TiN-EG纳米流体。对该流体进行辐射特性实验研究,测量纳米流体的半球透射率及反射率,计算得出其吸收率参数,并计算纳米流体对太阳辐射的吸收率。进行光学性能分析后,筛选出合适质量分数的纳米流体,通过自搭建的直接吸收式太阳集热系统,分流量对其性能进行验证,加入菲涅耳透镜聚光使流体出口温度达到中温水平。结果表明,太阳辐照度是系统温升直接影响因素,温度变化响应时间短;且太阳辐照度变化不大时,流体出口温升随着流量的降低而大幅攀升。同时系统连续运行5 h无异常,说明系统的稳定性及数据之可靠性。
The TiN-EG nanofluid with good stability was prepared by two-step method. The experimental study on the radiation characteristics of the fluid, measuring the hemispherical transmittance and reflectance of the nanofluid, calculated its absorption rate parameters, and calculated the nanofluid absorption rate of solar radiation. After analyzing the optical properties, the nanofluids with the proper mass fraction were screened out. The self-built direct absorption solar collector system was used to verify the performance of the nanofluid at the partial flow rate. The Fresnel lens was used to collect the nanofluids so that the fluid outlet temperature reached the mid-temperature level. The results show that the solar irradiance is the direct influencing factor of system temperature rise, and the response time of temperature change is short. When the solar irradiance changes little, the temperature rise of fluid outlet rises sharply with the decrease of flow rate. At the same time, the system runs continuously for 5 hours without any abnormality, indicating the stability of the system and the reliability of the data.